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%I #20 Aug 07 2023 02:13:09
%S 1,1,0,1,0,1,1,1,0,1,1,1,1,1,0,1,0,1,1,1,1,1,0,1,1,1,0,1,0,1,1,1,0,1,
%T 1,1,1,1,0,1,1,1,0,1,0,1,1,1,1,1,0,1,0,1,1,1,0,1,1,1,1,1,0,1,0,1,1,1,
%U 1,1,0,1,1,1,0,1,0,1,1,1,1,1,0,1,0,1,1,1,0,1,1,1,1,1,0,1,1,1,0,1,0
%N Characteristic function of A254614, numbers that are either odd or evil (or both).
%C A254614 is the complement of A128309 (even odious numbers).
%C A254379 is the characteristic function of A128309.
%H Antti Karttunen, <a href="/A254651/b254651.txt">Table of n, a(n) for n = 0..65537</a>
%H <a href="/index/Ch#char_fns">Index entries for characteristic functions</a>
%F a(n) = 1-A254379(n).
%e A254614 begins 0,1,3,5, hence this sequence begins 1,1,0,1,0,1.
%t a[n_] := If[OddQ[n] || !OddQ[DigitCount[n, 2, 1]], 1, 0]; Array[a, 100, 0] (* _Amiram Eldar_, Aug 07 2023 *)
%o (PARI) A254651(n) = bitor((n%2),!(hammingweight(n)%2)); \\ _Antti Karttunen_, Oct 01 2018
%o (Python)
%o def A254651(n): return (n&1^1)&n.bit_count()^1 # _Chai Wah Wu_, Mar 09 2023
%Y Cf. A128309, A254377, A254379, A254614, A254655 (run lengths).
%K nonn,base
%O 0
%A _Jeremy Gardiner_, Feb 04 2015
%E Name amended by _Antti Karttunen_, Oct 01 2018
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